#include <cstdio>
#define N 11000
#define exp 0.00000001
#define INF 10000.0
using namespace std;

int n, t;
int s[N], v[N];

int main() {
	// freopen("testdata.in", "r", stdin);
	// freopen("testdata.out", "w", stdout);
	freopen("dejavu.in", "r", stdin);
	freopen("dejavu.out", "w", stdout);
	scanf("%d%d", &n, &t);
	for (int i = 1; i <= n; ++i) {
		scanf("%d%d", &s[i], &v[i]);
	}
	double l = -INF, r = INF, mid, tmp = 0;
	while (l + exp <= r) {
		mid = (l + r) / 2;
		tmp = 0;
		for (int i = 1; i <= n; ++i) {
			if (mid + v[i] > 0)
				tmp += s[i] / (mid + v[i]);
			else {
				goto flag;
			}
		}
		if (tmp < t) {
			r = mid;
		}
		if (tmp > t) {
		flag:
			l = mid + exp;
		}
	}
	printf("%.7lf", l);
	fclose(stdin);
	fclose(stdout);
	return 0;
}